Insulated electrical connection



Dec. 19, 1967 R, R. AU 3,359,531

INSULATED ELECTRI CAL CONNECTION Filed Sept. 23, 1965 United States Patent 3,359,531 INSULATED ELECTRICAL CONNECTION Ralph Rupp Lau, Harrisburg, Pa., assignor to AMP Incorporated, Harrisburg, Pa.

Filed Sept. 23, 1965, Ser. No. 489,577 7 Claims. (Cl. 339213) ABSTRACT OF THE DISCLOSURE An insulated electrical connection is disclosed and is formed by applying an insulating cover to a previously connected terminal and wire conductor. By applying the terminal and insulating cover separately high crimping forces may be used for applying the terminal and low crimping forces may be used for applying the cover.

In the electrical connection field there have been numerous attempts to pre-insulate an electrical terminal wherein both the terminal ferrule and the insulating member are of open U-shaped configuration. Most such attempts, prior to this invention, have been unsuccessful for various reasons, some of which will become apparent as this discussion proceeds.

At present, when it is desired to pre-insulate a terminal having an open U-shaped ferrule-forming portion, it is the practice to take such a terminal and secure thereto a strip of insulating material. The terminal, with the insulating material thus secured, is then placed betv'veeri'the jaws of a crimping tool. An electrical eonductor- -is then inserted into the space formed by the open U, and the jaws of the crimpin'gftool are then closed so as'to accomplish in one operation the crimping ofboth the terminal and the insulating member to the electrical conductor. The force exerte'd by'the crimping tool is carried through the insulating member to the terminal, .thisbeing necessary because the terminal does not come into 'direct contact with the crimping tool. Examples of this type of operation are disclosed inUQS. Patents No. 2,786,191, granted to W. F. 'Broske, No. 2,845,606, granted to G. AxFull'en and'No. 3,048,650, granted to l. W. Allen et a1. The present invention. provides several distinct advantages over the prior art above referred to. In the prior art devices thepressure applied during the crimping operation must be held within close limits. The pressure must be: great enough to accomplish an effective crimp oftheferrule to the conductor but at the same time the pressure must be held below that point which would cause rupturing of the relatively fragile insulatingmate rial. This problemis avoided by the present invention wherein the crimping of the insulating member is accomplished in .a separate operation from the crimping of the ferrule, thereby permitting relatively high pressure during the ferrule crimping operation and relatively low pressure during the insulating member crimping operation. s

In the single stage operation there is a limited number or materials which can be used for the insulating material because such material must be capable of withstanding high crimping pressure without rupturing and the material must be capable of transmitting the forces from the crimping tool to the ferrule. In the present invention 3,359,531 Patented Dec. 19, 1967 these properties need not be possessed by the insulating material, the only essential requirement being that the material is an electrical insulator.

Another drawback of most known devices is that the terminals must be specially constructed and adapted to receive the insulating member. In contrast the present invention is designed for use with standard presently available terminals.

Also, the prior known devices in general require a step of securing the insulating material to the terminal prior to the crimping operation. This step is not necessary in practicing the present invention.

Reference is herein made to copending application Ser. No. 489,558, filed Sept. 23, 1965,. and assigned to the present assignee for a complete disclosure of one example of a method and machine for producing the article of the instant invention.

It is therefore an object of the present invention to provide an insulated electrical connection while avoiding the drawbacks of the known devices above referred to.

Another object is to provide for the insulating of stand ard terminals.

A further object is to provide an insulated electrical connection utilizing high crimping pressure on the terminal ferrule and low crimping pressure on the insulating member.

Other objects and advantages of the present invention will become apparent as the description proceeds.

In the drawings, in which like reference numerals refer to like parts:

FIGURE lis a perspective view of a pie-insulated electrical connection made in accordance with the teaching of this invention; 7

FIGURE 2 is a cross-sectional viewtaken along the line 22 of FIGURE 1;

FIGURE 3 is an exploded perspective view showing the several parts of the connection; and

FIGURE'4 isa sectional view 'of an alternative form of insulating material.

'The connecting device of the present invention consists (see FIGURE 3 of the drawing) of three elements, namely an electrical terminal 2, an electrical conductor 4, and an insulating member 6. The terminal is of standard open U-shaped ferrule configuration and consists of a tongue 8 and a ferrule-forming portion 10. The portion 10 terminates in two free ends or ears 12 and 14. The conductor 4 is made up of a wire portion 16 surrounded by an insulating casing 18. As shown a portion of the casing 18 has been stripped from the conductor to expose a length of bare wire. The insulating member 6 is of open U-shaped configuration and consists of a composite structure of a thin metallic member 20, such as brass, and a plastic insulating material 22 bonded thereto. The member 6 terminates in two free ends 24 and 26. FIG- URE 4 shows an alternative form of insulating member wherein a metallic member 28, such as steel, is completely surrounded by an insulating material 30. This latter configuration has the advantage of permitting the use of a metal which might normally be subject to corrosion were it not completely covered.

The particular insulating material used in member 6 may be chosen from a wide variety of materials. The material found to be especially suitable to use in the insulat- 3 ing member of FIGURE 3 is the material sold by E. I. du Pont de Nemours and Company Inc. under the registered trademark Mylar. In the modified form of FIG- URE 4 the material 30 is suitably polyvinyl chloride which is secured to the metallic member 28 by a fluidized bed process, such process being well known in the art.

FIGURE 1 shows the various parts making up the electrical connection in their assembled form. The stripped end of the conductor 4 is placed within the ferrule of the terminal 2 and the free ends 12 and 14 of the ferrule are bent over into engagement with the bare wire 16 and with each other, see also FIGURE 2. This bending over of the free ends is accomplished by a crimping operation. As stated previously, this crimping operation is effected in a first step which is completely independent of any operation on the insulating member 6. Therefore full crimping pressure may be developed in the crimping dies to insure a maximum mechanical and electrical connection between the terminal 2 and the conductor 4. Thereafter the terminal and conductor are placed in the insulating member 6 and the free ends 24 and 26 of member 6 are bent over into engagement with the outer surface of the ferrule 10 and with the outer surface of the insulating casing 18 on the conductor 4. This bending over of the ears of member 6 is accomplished in a separate crimping operation and can therefore be carried out at relatively low crimping pressure. This low crimping pressure avoids any possibility of rupturing the insulating member, which rupture might easily occur under high crimping pressure. The metallic member 20 thereafter remains in the bent over position and will exert a spring-like force on the ferrule and conductor by reason of the natural resiliency of the metallic member. This force will retain the member 6 in position, thus forming an insulation for the connection between the terminal 2 and the conductor 4.

It can be seen that the connecting device of the present invention utilizes a standard terminal and that no pretreatment of the terminal is necessary prior to its use, thereby materially decreasing the cost of the connecting device. Also there has not been any compromise of crimping pressure, such as is necessary when the terminal and insulating member are crimped in a single operation.

While certain specific materials have been mentioned in connection with the insulating member it is obvious that other materials could be used without departing from the scope or spirit of this invention. Also the electrical conductor need not be stripped prior to connection to the terminal but rather the terminal could be of the insulation piercing variety.

Various changes and modifications will occur to those skilled in the art without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims.

I claim:

1. An electrical connection comprising a terminal having a tongue portion and a ferrule portion, said ferrule being formed from an open U-shaped configuration, an insulated electrical conductor having the insulation striped from one end thereof to thereby expose a length of bare wire, said wire being disposed within said ferrule, the free ends of said ferrule being bent inwardly into engagement with said wire and with each other to form a permanent electrical and mechanical connection therewith, said ferrule having an internal surface completely surrounding said wire and an external closed surface, an insulating member formed from an open U-shaped configuration and receiving said ferrule, said insulating member comprising a composite structure of metallic and non-metallic material, the free ends of said member being bent inwardly into engagement with the external surface of said ferrule and with the insulation on said electrical conductor, whereby said insulating member completely surrounds said ferrule and is retained in position by a spring-like force exerted by said member on said ferrule and conductor.

2. An electrical connection comprising a terminal having a ferrule portion, said ferrule being formed from an open U-shaped configuration, an electrical conductor disposed within said ferrule, the free ends of said ferrule being bent inwardly into engagement with said conductor and with each other to form a permanent electrical and mechanical connection therewith, said ferrule having an internal surface completely surrounding said wire and an external closed surface, an insulating member formed from an open U-shaped configuration for receiving said ferrule and independently crimped thereto, the free ends of said member being bent inwardly into engagement with the external surface of said ferrule whereby said insulating member completely surrounds said ferrule and is retained in position by a spring-like force exerted by said member on said ferrule.

3. An electrical connection as set forth in claim 2 wherein said insulating member comprises a composite structure of metallic and non-metallic material.

4. An electrical connection as set forth in claim 2 wherein the free ends of said insulating member are in engagement with said conductor to retain said member in position relative to said conductor.

5. An electrical connection comprising an insulated conductor, an electrical terminal secured to said conductor, said terminal having a U-shaped ferrule portion crimped to said conductor to form a permanent electrical and mechanical connection therewith, said ferrule having an internal surface completely surrounding said wire and an external closed surface, and a U-shaped insulating member completely surrounding said ferrule and secured thereto, said insulating member comprising a composite structure of metallic and non-metallic material, said insulating member being independently crimped to said external surface of said ferrule and to said conductor to rigidly affix the insulating member thereto, said insulating member having its end portions bent inwardly into contact with the external surface of said ferrule, portions of said insulating member adjacent the crimped portion of the ferrule remaining out of contact with said ferrule.

6. An electrical connection comprising an insulated conductor having the insulation stripped from an end thereof exposing the wire therein, an electrical terminal having an open U-shaped ferrule-forming portion receiving said wire and crimped thereto to form an electrical and mechanical connection therewith, said ferrule having an internal surface completely surrounding said wire and an external closed surface, an open U-shaped insulating member receiving said terminal and conductor assembly and independently crimped thereto leaving portions of said insulating member adjacent the crimped portion of said member out of contact with both the external surface of said ferrule and with said conductor, said member completely surrounding said ferrule and having its end portions bent inwardly into contact with the external surface of said ferrule.

7. An electrical connection comprising an insulated electrical conductor having the insulation stripped from an end thereof exposing a length of bare wire, an electrical terminal comprising a tongue portion and an open U-shaped ferrule-forming portion, said latter portion receiving said length of bare wire and being crimped thereto to form a permanent electrical and mechanical connection therewith, said ferrule having an internal surface completely surrounding said wire and an external closed surface, an open U-shaped metallic member having a layer of insulating material bonded thereto, said member being of greater length than said ferrule-forming portion in an axial direction, said member receiving said conductor with the terminal attached thereto and being independently crimped, together with said insulating material, whereby the free ends of said U-shaped member are curled inwardly into contact with the insulation on said References Cited UNITED STATES PATENTS Shaw et al. 339-276 Swengel 339-276 Woolley 339-276 Broske 339-276 Broske 339-276 Vizcarrondo 339-256 X Fuller 339-276 Allen et al. 339-276 FRANCIS K. ZUGEL, Primary Examiner. MARVIN A. CHAMPION, Examiner. P. TEITELBAUM, Assistant Examiner. 

1. AN ELECTRICAL CONNECTION COMPRISING A TERMINAL HAVING A TONGUE PORTION AND A FERRULE PORTION, SAID FERRULE BEING FORMED FROM AN OPEN U-SHAPED CONFIGURATION, AN INSULATED ELECTRICAL CONDUCTOR HASVING THE INSUALTION STRIPPED FROM ONE END THEREOF TO THEREBY EXPOSE A LENGTH OF BARE WIRE, SAID WIRE BEING DISPOSED WITHIN SAID FERRULE, THE FREE ENDS OF SAID FERRULE BEING BENT INWARDLY INTO ENGAGEMENT WITH SAID WIRE AND WITH EACH OTHER TO FORM A PERMANENT ELECTRICAL AND MECHANICAL CONNECTION THEREWITH, SAID FERRULE HAVING AN INTERNAL SURFACE COMPLETELY SURROUNDING SAID WIRE AND AN EXTERNAL CLOSED SURFACE, AN INSULATING MEMBER FORMED FROM AN OPEN U-SHAPED CONFIGURATION AND RECEIVING SAID FERRULE, SAID INSULATING MEMBER COMPRISING A COMPOSITE STRUCTURE OF METALLIC AND NON-METALLIC MATERIAL, THE FREE ENDS OF SAID MEMBER BEING BENT INWARDLY INTO ENGAGEMENT WITH THE EXTERNAL SURFACE OF SAID FERRULE AND WITH THE INSULATION ON SAID ELECTRICAL CONDUCTOR, WHEREBY SAID INSULATING MEMBER COMPLETELY SURROUNDS 